In a fuel cell system, a circulation pump is generally used to recirculate and recycle an anode off-gas discharged from a fuel cell stack to a supply inlet of the fuel cell stack. The circulation pump has a motor, and the fuel gas exhaust is recirculated to the fuel cell stack by controlling the rotation speed of the motor. In this fuel cell system, when the temperature of the motor of the circulation pump exceeds a preset temperature level, output control of fuel cells may be performed to protect the motor from a potential damage.
Patent Document 1: Japanese Patent Laid-Open No. 2006-333543
Patent Document 2: Japanese Patent Laid-Open No. 2007-66554
Patent Document 3: Japanese Patent Laid-Open No. 2007-182900